The ratio of cars to trucks is 8 cars to 36 trucks. if there are 9 trucks, how many cars are there?

Set up the proportion with the numbers on top equalling the cars and the numbers on the bottom representing the trucks.

c equals the number of unknown cars.
To solve the proportion, cross multiply (multiply 8 by 9 and 36 by c) and solve for c.
72 = 36c
Divide 36 from both sides to get the answer.
c = 2
If there are 9 trucks, there are 2 cars.
You can check this by dividing 2 by 9, and dividing 8 by 36. Since they both equal the same number, this answer is correct.

Hope this helps =)